Additive manufacturing is a process of creating three-dimensional components by depositing overlapping layers of material under the control of a computer. One technique of additive manufacturing is known as direct metal laser sintering (DMLS). The DMLS technique uses a laser to direct a high-energy beam into a powdered metal medium at precise locations corresponding to features and dimensions of the component to be manufactured. As the energy beam contacts the powdered metal, the powdered metal is caused to melt and weld together and to previously melted layers of the component.
Conventional DMLS systems include a build chamber having a stage that is movable in a vertical direction, and an adjacent material chamber that holds the powdered metal. A recoater in the shape of a blade or a roller pushes powdered metal from the material chamber across the stage in the build chamber, thereby depositing a layer of the powdered metal of a desired thickness. After welding of the powdered metal by the laser (a.k.a., printing a layer of the component), the stage is lowered by an amount equal to a thickness of the next layer, and the process is repeated.
Although the conventional DMLS system produces components suitable for some applications, the system can also be problematic. In particular, as the recoater pushes material across the stage and the upper layer of the component in preparation for a subsequent melting event, the recoater exerts lateral forces on the component due to friction generated within the powdered metal. When manufacturing a component having a low aspect ratio (e.g., a small width-to-height ratio), these lateral forces have the potential to cause deformation or breakage of the component.
The conventional approach to reducing deformation or breakage of a low-aspect-ratio component is to simultaneously print sacrificial support structure around the component. This structure increases the aspect ratio of the component, thereby also increasing a lateral strength of the component. After manufacturing of the component and support structure is complete, the support structure is removed (e.g., etched, ground, and/or broken away from the component). While the conventional approach to reducing component deformation or breakage may be functionally adequate, the support structure is also resource (e.g., time and material) expensive.
An alternative method of providing support structure is disclosed in U.S. Patent Application Publication No. 2014/0333011 (the '011 publication) of Javidan et al. that published on Nov. 13, 2014. In particular, the '011 publication discloses an additive manufacturing method (e.g., a laser sintering method) used to create a three-dimensional object. The method includes forming a structure having multiple intersecting walls, and then inserting a prefabricated support piece into an interior cavity between the walls. Additional material is laid down on top of the walls and the support piece to create an overhang extending from the walls across the interior cavity. The support piece partially supports the overhang while the material cures to a solid state, thereby reducing a need to print support structure. The support piece is re-usable, thereby reducing material waste.
Although the method of the '011 publication may help to reduce resource wasting associated with an additive manufacturing process, application of the method may be limited. Specifically, the method may only be applicable to creation of an overhang. In addition, the method may provide little, if any, lateral strength increase to a component having a low-aspect ratio.
The disclosed additive manufacturing system is directed to overcoming one or more of the problems set forth above and/or other problems of the prior art.